A zirconium/metal oxide fibre comprises zirconium oxide and a metal oxide. The fibre has sufficient structural strength such that for example it may be used as a substitute fibre for glass fibre in the manufacture of paper and paper-like materials. Preferably the fibre""s thickness is substantially uniform and has a length in excess of 1 micron.
The metal oxide fibre is made by adding a metal oxide in a suitable form, preferably as a solution of the metal salt (or a colloidal dispersion of the metal) to a colloidal dispersion comprising an amorphous zirconium polymer of the formula:
[Zr4(OH)12(X)2(H2O)4]n(X)2n.2nH2Oxe2x80x83xe2x80x83(I) 
wherein X is a zirconium polymer compatible anion and n is a whole number.
The mixed colloidal dispersion is subsequently made into a mixed metal oxide fibre. Preferably the colloidal dispersion of the zirconium polymer of formula (I) is made in accordance with a modification to the process described in U.K. Patent 1,181,794 where, for example, zirconium carbonate or zirconium hydroxide is reacted to form the colloidal dispersion containing the polymer of formula (I).
According to a most preferred embodiment, the invention relates to a zirconium/metal oxide fibre that comprises zirconium oxide and a lanthanide oxide. Preferably, the lanthanide/zirconium oxide fibre is made by adding a solution of a lanthanide, most preferably lanthanide nitrate (or a lanthanide colloidal dispersion) to a colloidal dispersion comprising an amorphous zirconium polymer of the formula:
[Zr4(OH)12(NO3)2(H2O)4]n(NO3)2n0.2nH2Oxe2x80x83xe2x80x83(I) 
The lanthanide nitrate solution is preferably formed by reacting a lanthanide carbonate, hydroxide or oxide with nitric acid.
It was surprisingly found that one could add a highly concentrated solution of a metal salt (or metal oxide colloidal dispersion) to the colloidal dispersion of zirconium polymer of formula (I) creating a mixed colloidal dispersion whereby the charge balance remains intact preventing adverse precipitation within the mixed colloidal dispersion. The preferred ratio of X to zirconium in the polymer of formula (I) is in the range of about 1.0:0.98 to 1.0 to 1.3 to ensure the colloidal dispersion formation although, for reasons later discussed, the ratio may fall outside this range. The pH of the colloidal dispersion is preferably in the range from about 1.5 to about 2. Due to the viscoelastic properties of the zirconium polymer of formula (I), the zirconium polymer of formula (I) can act as a spinning aid such that the concentrated mixed colloidal dispersion has a viscoelasticity that is suitable for fibre formation by techniques such as spray drying, drawing or blow spinning. The resultant green fibres are of a stable dried gel. These green fibres are heat treated to drive off volatiles to form crystalline fibres comprising zirconium oxide and metal oxide.
Although the zirconium polymer of formula (I) has a viscoelasticity that is suitable for fibre formation on its own, other spinning agents may be incorporated into the mixed colloidal dispersion such that the synergistic combination of both the zirconium polymer of formula (I) and at least one other spinning agent facilitates fibre formation. Preferably, these other spinning aids are organic based and are fugitive (volatile) during heat treatment. Examples of exemplary spinning aids include polyethylene oxide and polyvinylpyrrolidone.
It is known that metal oxide catalysts can be incorporated on the surface of various types of fibres for decomposing various compositions or for purifying exhaust gases. For example, U.S. Pat. No. 5,094,222 describes a mixture of ceramic fibres containing an oxidation catalyst for decomposition of fats and oils. The ceramic fibres are made from at least one of the following oxides: silicon oxide, zirconium oxide and aluminum oxide. The oxidation catalyst can be selected from at least one of a variety of metal oxides. U.S. Pat. No. 5,165,899 describes a porous fibrous structure for purification of exhaust gases. The fibrous structure is made of metal alloy fibrils of the MCrAlX type where M is a matrix chosen from iron, and/or nickel and/or cobalt and X is chosen from zirconium, yttrium, cerium and lanthanum metal. Japanese Patent 3,060,738 describes cerium oxide mixed and other components which were mixed with an alumina-silica ceramic fibre to provide a catalyst that decomposes soot. Also, U.S. Pat. No. 3,860,529 describes Group III B metal oxide impregnated zirconia fibres.
Metal oxide catalysts have also been used in an extruded form. Canadian Patent 2,274,013 describes an extruded form of a ceria/zirconia mixture to treat exhaust gases.
Similarly, metal oxide catalysts can also be used as coatings on various types of fibres for primarily purifying exhaust gases. See for example U.S. Pat. Nos. 5,040,551; 5,075,275; 5,195,165; 5,759,663; 5,944,025; 5,965,481 and U.K. Patent 2,236,493. For instance, to purify exhaust gas, U.S. Pat. No. 5,075,275 describes a catalyst carrier, such as porous heat resistant fibres, which have been coated with cerium and barium oxides. U.S. Pat. No. 5,759,663 describes a high temperature resistant lath of woven ceramic where the fibres of the lath are coated with chromium oxide, silicone carbide and cerium oxide. U.K. Patent 2,236,493 describes a honeycomb filter impregnated with cesium, copper, and cerium or lanthanum to oxidize carbonaceous particles.
All of the above-mentioned references either refer to metal oxides as incorporated on the surface of fibres, as an extruded form, as coatings on fibres, or as impregnating the fibre. Several references exist that refer to metal oxides in fibre form only and further describe various processes for making such fibres. For instance, U.S. Pat. No. 5,911,944 describes a fibre made by dispersing a raw material containing at least one metal hydrate and hydrated metal compound in an alcohol-based solvent (Bpt. greater than 70xc2x0 C.) forming a colloidal dispersion. The colloidal dispersion is heated not higher than 100xc2x0 C., which produces a polymer of the raw material. The polymer is converted to a complex. The complex is concentrated until it has spinnability. The colloidal dispersion is stretched to form a fibre precursor that causes gelation. The gelatinized fibre precursor is heated to produce a fibre. U.S. Pat. No. 3,846,527 describes making inorganic fibres that normally would not be spinnable. This was done by dry spinning a solution or colloidal dispersion with a linear polymeric fibre-forming material. U.K. Patent 1,402,544 describes the preparation of mixed metal oxide fibres by using metal alkoxide(s) capable of converting to spinels. Rare-earth metals are not known to form spinels. U.K. Patent 1,322,723 describes a process for producing fibrous material wherein zirconium oxide is capable of reacting chemically with silica fibrils to assist in bonding the fibrils together.
U.K. Patent 2,059,933 describes the preparation of alumina or zirconia fibres by spinning an aqueous solution of the corresponding metal salt, a precursor to the metal oxide fibre. The specific examples relate only to formation of alumina fibres. These particular fibres can be made from an aqueous solution containing other metals whose salts are hydrolysed at a pH less than 7 to yield a mixed metal fibre. To prevent gelling or precipitation within the aqueous solution, aliphatic or aromatic amines are added to the solution to remove excess anions to create a more desirable solution for fibre formation. In the present invention, however, excess nitrate anions within the zirconium polymer colloidal dispersion, as described in U.K. Patent 1,181,794, result in formation of spheres that would be detrimental to formation of our desired mixed metal oxide fibres.
Several patents have dealt with a Group IIA, a Group IIIA or a lanthanide metal oxide colloidal dispersion that can form gels, which can be used to make ceramic materials as described in U.S. Pat. No. 4,181,532. These colloidal dispersions can also be used as coatings, as described in U.S. Pat. No. 4,231,893. U.S. Pat. No. 4,356,106 describes a process for making a colloidal dispersion that involves using dry cerium oxide hydrate and a deaggregating agent to form a dry dispersible cerium compound.
Several references exist that refer, specifically, to various processes for making metal oxide/zirconium oxide fibres. U.S. Pat. No. 5,468,548 describes making reinforced fibres for high temperature composites consisting of a matrix and eutectic fibres dispersed in the matrix. The eutectic fibres can be selected from a series of metal oxides and the reference suggests several optional metal oxides including ceria and zirconia. The matrix and fibres are very specific in that the coefficient of thermal expansion of the matrix should be similar to the eutectic fibre. U.S. Pat. No. 3,891,595 discusses making friction materials that contain 40-85% of a synthetic inorganic refractory metal oxide fibre and 15-35% of a binder. The metal oxide fibre may contain zirconia and 1-10% of a stabilizer, such as alkaline oxides, yttria and rare earth oxides. xe2x80x98Stabilizersxe2x80x99 determine the crystal structure, e.g. tetragonal or cubic, and prevent the formation of the monoclinic crystal structure of zirconia. Stabilizers may also suppress growth of crystallites. A typical binder is a phenol-formaldehyde resin. U.S. Pat. No. 3,992,498 describes preparation of a fibre by making a solution of a polar solvent, a metal compound and an organic polymer. The metal can be zirconium. The solution is extruded into at least two gas streams and partially dried. The solution may also contain a lanthanide metal as a phase stabilizer or as a luminescent salt. U.S. Pat. Nos. 4,927,622, 5,053,214 and 5,112,781 describe a process that involves making an aqueous solution of zirconium-based granules and a phase stabilizer (1-35 wt %), such as calcium, yttrium, cerium and hafnium oxides, and fiberizing the solution. This particular process involves making and drying the zirconium-based granules before making the fibre. U.S. Reissued Pat. No. 35,143 describes a process for making a ceramic fibre that involves mixing crystalline zirconium grains, a zirconia compound, solvent and a phase stabilizer (more than 0 and up to 20 mol % of the stabilizer).
There are also several patents that discuss formations of colloidal dispersions of mixed metal oxides. For instance, U.S. Pat. No. 4,788,045 describes preparing a stabilized zirconia powder that involves mixing a zirconia hydrate colloidal dispersion (pH 0.5-5), containing acicular crystals with dimensions ranging from 10 to 50 nm, with a solution of a stabilizer such as cerium ( less than 30 mol %). The powder formed can be used in ceramics. U.S. Pat. No. 5,004,711 describes forming a zirconia colloidal dispersion from a solution containing a zirconium salt and a stabilizer, such as yttrium, lanthanum, cerium, calcium and magnesium oxides. The solution is mixed with a strong base anion-exchange resin and the resulting colloidal dispersion is recovered. U.S. Pat. No. 5,238,625 describes a process for making a stabilized zirconia colloidal dispersion, which involves hydrolyzing a zirconium alkoxide using aqueous hydrogen peroxide in the presence of an acid and a stabilizing agent to form a hydrolysate. The hydrolysate is evaporated to form a dried hydrolysate, which is redissolved into an organic solvent.
The present invention employs the colloidal dispersion of an amorphous zirconium polymer of formula (I), which was described in U.K. Patent 1,181,794. Although this U.K. patent describes that a few percent by weight of a stabilizer such as lime or yttria may be added to the polymer of formula (I), it does not contemplate the addition of excessive amounts of the metal to the polymer of formula (I). In this respect, it was generally understood that the addition of higher proportions of metals would destroy colloidal dispersions, such as those of the polymer of formula (I).
According to an aspect of the invention, there is provided a process for making a zirconium/metal based fibre, the process comprising:
i) mixing a metal salt solution or metal oxide colloidal dispersion, wherein the metal is selected from the group consisting of at least one of a Group IIA metal, a transition metal, a Group IIIA metal and a Group IIIB metal, with a colloidal dispersion of an amorphous zirconium polymer of the formula:
[Zr4(OH)12(X)2(H2O)4]n(X)2n.2nH2Oxe2x80x83xe2x80x83(I) 
wherein X is a zirconium polymer compatible anion and n is a whole number from 1 to less than 200, to provide a mixed colloidal dispersion; and
forming the mixed colloidal dispersion into the zirconium/metal based fibre.
According to another aspect of the invention, X is selected from the group consisting of NO3xe2x88x92, Clxe2x88x92 and ClCH2COOxe2x88x92 and more preferably, n is a whole number from 1 to about 100.
According to another aspect of the invention, the colloidal dispersion of the zirconium polymer has a ratio of X to zirconium in the range of about 1.0 to 0.98 to about 1.0 to 1.3 to maintain the polymer colloidal dispersion.
According to another aspect of the invention, the colloidal dispersion of the zirconium polymer has a pH in the range of about 1.5 to about 2.0 to maintain the polymer colloidal dispersion.
According to yet another aspect of the present invention, the metal is a lanthanide metal.
According to yet another aspect of the present invention, the metal is selected from the group consisting of at least one of cerium, yttrium, scandium, magnesium and calcium.
According to yet another aspect of the present invention, the metal salt solution is selected from the group consisting of at least one of a metal nitrate, metal chloride, metal acetate and metal perchlorate.
According to yet another aspect of the present invention, the metal oxide colloidal dispersion is made from a metal salt substrate selected from the group consisting of at least one of a metal nitrate, metal chloride, metal acetate and metal perchlorate.
According to yet another aspect of the present invention, at least one fugitive spinning agent is included in the mixing step. The fugitive spinning agent may be selected from the group consisting of polyvinyl pyrrolidone, polyethylene oxide, polyvinylalcohol, polyurethane, polyacrylic acid salt, polyacrylamide and polyvinylmethyl ether.
According to another aspect of the invention, the step of forming the fibre includes: concentrating the mixed colloidal dispersion of step i) such that the mixed colloidal dispersion becomes viscoelastic and forming the mixed viscoelastic colloidal dispersion into the fibre. Preferably, the mixed viscoelastic colloidal dispersion has a concentration ranging from about 300 g/L to 600 g/L.
According to another aspect of the invention, the fibre diameter is controlled by conventional drawing of said mixed viscoelastic colloidal dispersion.
According to another aspect of the invention, the fibre is dried and fired to form a crystalline zirconium oxide/metal oxide fibre. Preferably, the fibre is a zirconium oxide/cerium oxide fibre.
In yet another aspect of the invention, there is provides a use of an amorphous viscoelastic zirconium polymer of the formula:
[Zr4(OH)12(X)2(H2O)4]n(X)2n.2nH2Oxe2x80x83xe2x80x83(I) 
wherein X is a zirconium polymer compatible anion and n is a whole number from 1 to less than 200, as a spinning aid for making a zirconium/metal based fibre.
In yet another aspect of the invention, there is provided a synergistic combination of at least one fugitive spinning aid with an amorphous viscoelastic zirconium polymeric inorganic spinning aid of the formula:
[Zr4(OH)12(X)2(H2O)4]n(X)2n.2nH2Oxe2x80x83xe2x80x83(I) 
wherein X is a zirconium polymer compatible anion and n is a whole number from 1 to less than 200, said combination being suitable for forming a zirconium/metal based fibre.
In yet another aspect of the invention, there is provided a green zirconium/metal based fibre comprising a mixed colloidal dispersion of a metal, wherein said metal is selected from the group consisting at least one of a Group IIA metal, a transition metal, a Group IIIA metal and a Group IIIB metal, and an amorphous zirconium polymer of the formula:
[Zr4(OH)12(X)2(H2O)4]n(X)2n.2nH2Oxe2x80x83xe2x80x83(I) 
wherein X is a zirconium polymer compatible anion and n is a whole number from 1 to less than 200.
According to another aspect of the invention, X is selected from the group consisting of NO3xe2x88x92, Clxe2x88x92 and ClCH2COOxe2x88x92 and more preferably, n is a whole number from 1 to about 100.
According to another aspect of the invention, the metal of the zirconium/metal based fibre is selected from the group consisting of at least one of a Group IIA metal, a transition metal, a Group IIIA metal and a Group IIIB metal. Preferably, the metal of the zirconium/metal based fibre is a lanthanide metal. More preferably, the metal of the zirconium/metal based fibre is selected from the group consisting of at least one of cerium, yttrium, scandium, magnesium and calcium.
According to another aspect of the invention, the metal of the zirconium/metal based fibre is present in up to 50 weight % of the total equivalent zirconium oxide content.
According to another aspect of the invention, the formula has a ratio of X to zirconium in the range of about 1.0 to 0.98 to about 1.0 to 1.3.
Accordingly, the present invention relates to a novel amorphous, green zirconium/metal fibre. The green fibre is a precursor to a zirconium/metal oxide fibre. Additionally, the present invention relates to a process for making such fibres and the general use of an amorphous zirconium polymer as a spinning aid.
The fibre is made by adding a solution of a metal salt solution (or a metal oxide colloidal dispersion) to a colloidal dispersion comprising an amorphous zirconium polymer of the formula:
[Zr4(OH)12(X)2(H2O)4]n(X)2n.2nH2Oxe2x80x83xe2x80x83(I) 
wherein X is a zirconium polymer compatible anion in providing a colloidal dispersion. The anion is an ionic constituent which ensures the formation of a stable dispersion. The anion is derived from a conjugate acid that provides pH in the dispersion which is most preferably about 1.5 to 2. Preferred anions may be selected from the group consisting of nitrate, chloride and chloroacetate. In formula (I), n is a whole number and preferably ranges from 1 to less than 200 and, preferably, from 1 to about 100.
The mixing is preferably done at a temperature from about 0 to 90xc2x0 C., more preferably, from about 15 to 25xc2x0 C. The preferred ratio of X to zirconium in the polymer of formula (I) is such that it ensures colloidal dispersion formation. The ratio of X to zirconium is, preferably, about 1.0:0.98 to about 1.0 to 1.3. However, it is understood the ratio of X to zirconium may fall outside this range, providing the resultant polymer of Formula I remains intact. The pH of the colloidal dispersion may preferably range from about 1.5 to about 2. The mixed colloidal dispersion is then concentrated, made into the green fibre, which is subsequently made into the zirconium/metal oxide fibre.
The colloidal dispersion of the zirconium polymer of formula (I) may be made in accordance with a modification to the process described in U.K. Patent 1,181,794. In order to facilitate an understanding of that process, it is outlined as follows. A dispersion or slurry of zirconium carbonate or zirconium hydroxide is reacted with an approximate equimolar amount of conjugate acid of the anion X which is preferably nitric acid, hydrochloric acid or chloroacetic acid, to provide the polymer of formula (I). The reaction is preferably carried out at about 50xc2x0 C. to 70xc2x0 C. with agitation. The reaction mixture is preferably maintained at a pH of about 1.5 to about 2.0 with an X to zirconium mole ratio of about 1.0:0.98 to about 1.0:1.3. These preferred conditions provide for the polymer formation and its stability in the dispersion.
The metal salt solutions that are useful for the preparation of the metal oxide fibre of this invention include a salt solution of at least one of a Group IIA metal, a transition metal, a Group IIIA metal and a Group IIIB metal. In particular, the metal salt solution may be made from the following metal salts: YCl3, Y2(CO3)3, Y(C2H3O2)3, Y(NO3)3, CaCl2, CaCO3, Ca(C2H3O2)2, CaClO4, Ca(NO3)2, MgCl2, MgCO3, Mg(C2H3O2)2, Mg(ClO4)2, Mg(NO3)2, CeCl3, Ce2(CO3)3, Ce(C2H3O2)3, Ce(ClO4)3, and Ce(NO3)3.
In accordance with this invention, the solution of the metal salt is added to the colloidal dispersion of zirconium polymer of formula (I). A mixed colloidal dispersion is formed whereby the charge balance remains intact, preventing adverse precipitation within the mixed colloidal dispersion. This unexpected stability of the mixed colloidal dispersion is quite surprising. Thus, at least one type of metal salt solution may be added to the amorphous zirconium polymer to yield up to 50 weight % of the total equivalent zirconium/metal oxide content in the fibre. More preferably, the metal salt solution is added to yield up to 25 weight % of the total equivalent zirconium/metal oxide content in the fibre.
Metal oxide colloidal dispersions useful for the preparation of the metal oxide fibre of this invention include at least one of a Group IIA metal, a transition metal, a Group IIIA metal and a Group IIIB metal oxide colloidal dispersion. In particular, the metal oxide colloidal dispersion may be made from the following metal salts: YCl3, Y2(CO3)3, Y(C2H3O2)3, Y(NO3)3, CaCl2, CaCO3, Ca(C2H3O2)2, CaClO4, Ca(NO3)2, MgCl2, MgCO3, Mg(C2H3O3)2, Mg(ClO4)2, Mg(NO3)2, CeCl3, Ce2(CO3)3, Ce(C2H3O2)3, Ce(ClO4)3, and Ce(NO3)3.
Preferably, the metal oxide colloidal dispersion is made by mixing an aqueous slurry of the metal salt with an acid to yield a hydrolyzable salt. The preferred acids are nitric acid or hydrochloric acid. Alternatively, if the initial metal salt is a nitrate or a chloride, this step of mixing the nitrate or chloride salt with acid is unnecessary. By either approach, the resulting hydrolyzable salt such as metal nitrate or metal chloride is hydrolyzed. Preferably, it is hydrolyzed and oxidized by adding a mixture of ammonium hydroxide and hydrogen peroxide. A metal hydroxide is obtained and admixed with water and a strong acid to yield a slurry. The strong acid may be, for example, nitric acid, hydrochloric acid or perchloric acid, and is capable of deaggregating the resulting insoluble metal hydrate. A residue from the slurry is then admixed with water to give the metal oxide colloidal dispersion.
Again, by adding the metal oxide colloidal dispersion to the colloidal dispersion of zirconium polymer of formula (I), a mixed colloidal dispersion is created. Surprisingly, the charge balance remains intact, preventing adverse precipitation within the mixed colloidal dispersion. Thus, the metal oxide colloidal dispersion may be added to the amorphous zirconium polymer to yield up to 50 weight % of the total equivalent zirconium/metal oxide content in the fibre. More preferably, the metal oxide colloidal dispersion is added to yield up to 25 weight % of the total equivalent zirconium/metal oxide content in the fibre.
Cerous and/or ceric salts can be converted into cerium (IV) colloids relatively easily, which, like the cerium (III) salt solutions, can be readily mixed with the zirconium polymer of formula (I) without serious adverse effect on the dispersion. For example, in one particular embodiment, a zirconium/cerium oxide fibre is made by adding a solution of cerium nitrate to the polymer of Formula (I). The cerium nitrate solution is made by mixing cerium carbonate with nitric acid or by dissolving cerium nitrate in water. The solution is then admixed with a colloidal dispersion comprising the preferred amorphous zirconium polymer of the formula:
[Zr4(OH)12(X)2(H2O)4]n(X)2n.2nH2Oxe2x80x83xe2x80x83(I) 
wherein X is preferably NO3xe2x88x92. The mixing is done at approximately 15 to 25xc2x0 C.
In a second embodiment, a zirconium/cerium oxide fibre is made by an alternative route. The zirconium/cerium oxide fibre is made by adding a colloidal dispersion of cerium nitrate to the zirconium polymer of formula (I). The dispersion is made by admixing an aqueous slurry of cerium carbonate with nitric acid. The resulting cerium nitrate is hydrolyzed and oxidized through the addition of a mixture of ammonium hydroxide and hydrogen peroxide. Cerium (IV) hydroxide is obtained and admixed with water and nitric acid to yield a slurry. A residue from the slurry is admixed with water to give the cerium oxide colloidal dispersion. The cerium oxide colloidal dispersion is then added to a colloidal dispersion comprising the preferred amorphous zirconium polymer of the formula:
[Zr4(OH)12(X)2(H2O)4]n(X)2n.2nH2Oxe2x80x83xe2x80x83(I) 
wherein X is preferably NO3xe2x88x92. The mixing is done at approximately 15 to 25xc2x0 C.
In general, the mixed colloidal dispersion of this invention is fiberized by concentrating the mixed dispersion such that it has a viscoelasticity that is suitable for fibre formation by techniques such as spinning, drawing, blowing or extrusion. Preferably, the concentrated mixed colloidal dispersion has a viscosity of at least 0.8 poise, more preferably 0.8 to 5.0 poise and most preferably 0.8 to 2.5.
The fibre diameter is controlled by conventional drawing techniques such as pulling or drawing, centrifugal spinning, nozzle injection or blow spinning. Preferably, the polymer solutions are spray-dried by centrifugal spinning, nozzle injection or disc atomization to give fibres several centimeters long. Most preferably, these fibres have less than 15% non-fibrous material.
The resultant amorphous, green fibres are of a stable dried gel. These green fibres are heat treated, preferably to 500xc2x0 C., to drive off volatiles to form crystalline fibres comprising zirconium oxide and the selected metal oxide. The crystalline fibres formed have a tetragonal crystal structure. However, as the metal oxide concentration increases beyond 50% by weight of the total equivalent zirconium/metal oxide content, the crystalline fibres tend towards a cubic crystal structure.
Specifically, the mixed colloidal dispersion is capable of being spun into a fibre due to the viscoelastic properties of the zirconium polymer of formula (I) itself. The metal salt solution (or the metal oxide colloidal dispersion) lacks the viscoelastic properties for conversion alone into a fibre. Through addition of the metal salt solution (or the metal oxide colloidal dispersion) to the colloidal dispersion of the zirconium polymer of formula (I), the polymer can act as a spinning aid such that the concentrated mixed colloidal mixture can become viscoelastic and hence, spinnable.
Although the zirconium polymer of formula (I) has a viscoelasticity that is suitable for fibre formation, other spinning agents may be incorporated into the mixed colloidal dispersion such that the synergistic combination of both the zirconium polymer of formula (I) and at least one other spinning agent facilitate fibre formation. Preferably, these other fugitive spinning aids are organic based and hence dissipate during heat treatment. Suitable spinning aids include polyvinyl pyrrolidone, polyethylene oxide, polyvinylalcohol, polyurethane, polyacrylic acid salt, polyacrylamide and polyvinylmethyl ether.
In a preferred embodiment, 1.5% of polyethylene oxide (molecular weight is 5,000,000) is added to the mixed colloidal dispersion.
In general, the fibers may be formed by spraying a conditioned feed using a Mobile Minor spray dryer made by NIRO of Wisconsin, United States. The conditioned feed, for example, may be formed by concentrating a colloidal dispersion such that the dispersion has a viscoelasticity suitable for fibre formation or it may be formed by adding a spinning aid to the colloidal dispersion such that the dispersion has a viscoelasticity suitable for fibre formation. The conditioned feed is pumped at a rate of 1.0 L/hour to the dryer that has been fitted with disc atomization or nozzle injection. The inlet temperature is maintained in the range of 150xc2x0 C. to 280xc2x0 C. with the outlet temperature in the range of 80xc2x0 C. to 110xc2x0 C.
The following Examples are being submitted to further illustrate various aspects of the present invention. These Examples are intended to be illustrative only and are not intended to limit the scope of the present invention.